We all know that exercise is an excellent way to improve our brain health and can even delay or prevent the onset of dementia. However, much less is known as to whether exercise makes a difference when we have dementia.
Is it still worth it doing exercise then and what impact does it have on the cognitive and behavioural symptoms? A recent study provides definite evidence to these questions.
Exercise is a critical aspect of keeping us healthy when we age. Not only does exercise improve the health of our heart and blood vessels, so-called cardiovascular health (from Greek cardio = ‘heart’ and Latin vasculum = ‘vessel), but it also positively affects our brain health. There is abundant scientific evidence that brain health is greatly improved in older people if they exercise regularly. It is therefore no wonder that the common notion these days is ‘what’s good for the heart is good for the brain’.
But what do we mean by exercise?
There are various ways to define exercise but the simplest is that it is ‘structured physical activity’. Physical activity refers to any movement we do throughout the day, ranging from getting up from bed to walking to the shop, pottering around in the house, gardening or taking the dog for a walk. Exercise can be regarded as a part of physical activity but instead of everyday physical activity, it is much more structured physical activity. For example, all sports and their training fall under exercise as those are all structured physical activities.
Staying physically active and doing exercise has been shown to be very important for healthy ageing. If we stay physically active we reduce our risk for cardiovascular diseases, such as heart attacks or strokes, by a staggering 40%. The mechanisms for physical activity on our cardiovascular healthy are manifold, including improving the health of our heart, our blood vessels and even our blood pressure.
What has this to do with the brain?
Many people do not know that the brain is the largest ‘consumer’ of oxygen and glucose (sugar) in the whole body. Our brain requires therefore a consistent and large blood flow, as the blood provides the oxygen and glucose for the brain cells. Not surprisingly, the brain has therefore a very large network of blood vessels supplying it with oxygen and glucose. However, if our heart or blood vessels are not healthy, the supply of oxygen and glucose is reduced in the brain. In the worst cases, there is blockage or break in the large blood vessels supplying the brain, which causes a stroke in the brain affecting many brain regions.
However, for dementia, it is actually the blockage or breakage of very small blood vessels which is far more important. If those tiny blood vessels get blocked or break, it causes so-called mini-strokes in a very small region in the brain. Such mini-strokes are commonly not noticed by people having them, which makes them so dangerous, since we can have multiple mini-strokes over the years without us noticing them. The key to dementia is that the number of mini-strokes increases our risk of dementia directly. This means the more mini-strokes we have the higher risk of us developing dementia subsequently. Keeping our heart healthy is therefore critical for dementia prevention.
This brings us nicely back to exercise, as we know already that exercise improves our cardiovascular health and concsequently our brain health, as we are less likely to have such mini-strokes in the brain, in turn reducing our risk for dementia.
This is all very well if we want to prevent dementia but does exercise make a difference when we actually have dementia?
This simple question has been discussed for many years, as there are clear benefits for people with dementia to stay physically active but how about exercise? Would exercise for example slow down the cognitive or behavioural symptoms changes?
A new study addresses this point precisely, by conducting a systematic review across all existing clinical trials conducting exercise in people with dementia. As a reminder, a systematic review examines all the existing evidence and therefore provides definite evidence across all previous research studies as to whether a therapy or treatment is beneficial or not.
The findings of the study show that across all studies (46 trials, including 5099 people with dementia) there is a beneficial effect for cognitive health in dementia. The cognitive improvements are not only present for the mild stages of dementia but even for moderate stages of dementia. This is an important finding as it shows that cognitive decline can be slowed down by exercise even when we are in the moderate stage of dementia.
More severe dementia was not taken into account as there are no studies to date investigating exercise in the severe stages of dementia. The main reason is that people with severe dementia have often limited mobility or are bedridden, which makes exercise interventions more challenging.
The study also found that behavioural symptoms are reduced by exercise. Unfortunately, the researchers did not state which specific behavioural symptoms were affected, so we do not know which specific behavioural symptoms are particularly reduced by exercise. The researchers also caution in their study that the positive effects for behaviour were more variable across studies, so the jury might be still out on whether exercise truly has a beneficial effect on behaviour.
Still, these are very promising findings showing that exercise has not only a benefit for our physical but also cognitive health and potentially even reducing behavioural symtpoms.
In terms of the type of exercise, the study looked across clinical trials using 3 types of exercise: 1) aerobic, 2) strength and 3) a combination of aerobic and strength. From the results, aerobic exercise emerged as the best for cognitive health. This makes sense since aerobic exercise is best for our cardiovascular system and therefore our brain.
However, we should not dismiss strength training, such as yoga, pilates and using weights. Strength training is excellent for our core muscles which improve our core strength and balance, in turn reducing our risk for falls. Based on this, ideally, we should consider a combination of aerobic and strength exercise as part of our weekly routine.
The final important results were that the intensity of the exercise also played a critical role in the cognitive and behavioural benefits. While mild exercise intensity showed positive effects, the effects were largest for more moderate intensity exercises.
But before you run now off and start exercising vigorously, please talk first to your physician to check that it is okay for you to exercise, in particular at moderate intensity. The last thing we want to do is to start vigorously and then injure ourselves, which would lead us to do actually less exercise or even cause other health problems. If there is one advice I would give to people who consider doing more exercise it is: ‘Take it slowly but exercise consistently’. Sports scientists recommend not to increase our exercise activity by more than 10% at a time, hence if we start from no or very little exercise we need to take it very easy and slow to build up our exercise activity.
Overall, the research findings are very promising and exciting by showing that it is worth to do exercise when we have mild to moderate dementia. It will not only improve our physical health but also our mental health, with improved cognition and reduced behavioural symptoms.
Certainly worth considering to dust off those trainers in the cupboard.
Law CK, Lam FM, Chung RC, Pang MY. Physical exercise attenuates cognitive decline and reduces behavioural problems in people with mild cognitive impairment and dementia: a systematic review. J Physiother. 2020 Jan;66(1):9-18. doi: 10.1016/j.jphys.2019.11.014. Epub 2019 Dec 13. PMID: 31843427.
